1. Technical Field of the Invention
This application relates to electric circuit card mounting apparatus and, in particular, to apparatus for facilitating the alignment of electrical circuit cards with a plurality of backplane-mounted pin contacts.
2. Description of the Prior Art
Present systems employed for mounting circuit cards require rather close tolerances on the assembled parts of the mounting apparatus to assure proper alignment of the circuit card edge-mounted connector with a field of contacts in the backplane. In some instances, as exemplified by K. H. Pohl, U.S. Pat. No. 3,320,483 issued May 16, 1967, support members have been disclosed for card-edge type connectors. In Pohl the support member comprises an elongated holder body with a pair of tongues molded at the top and bottom. These tongues snap-mount around mating bosses provided on the carrier or frame. An inner chamber of each holder formed by the side and front walls includes a number of wedge-shaped lips through which the connector block may be forced and, once behind them, retained. Extension of either or both of the sidewalls of the holder provides protection for the connector block terminals.
Another example of circuit card mounting apparatus is disclosed in J. Andreini et al, U.S. Pat. No. 3,559,234, issued Aug. 10, 1971. This reference relates to a receptacle for modular circuit elements. The receptacle includes spaced sides having opposed grooves, each side having a plurality of spaced, parallel struts extending rearward of the grooves. The grooves accommodate lateral edges of the circuit card to guide it into engagement with the connector extending between the sides. Each end of the connector has a pair of tines that are accommodated by the spaces between the struts. The tines at one end of the connector include lips that extend behind the struts and secure the connector in place.
Similar apparatus is disclosed in J. Andreini et al Defensive Publication No. T876,004, published July 28, 1970. While the Andreini et al defensive publication is primarily directed to apparatus for locking a circuit card to a mounting, a slotted card guidance arrangement is suggested.
Although each of the foregoing references discloses a practical solution to the particular problem faced, the problem of requiring close tolerances on each of the pieceparts used to fabricate circuit card mounting assemblies persists. In particular, the problem of ensuring accurate alignment of a circuit card edge-mounted connector with several hundred pin contacts mounted in a backplane without the need for very close tolerances of the assembled pieceparts remains a constant source of concern to physical designers. Efforts to alleviate this problem dictate that a circuit card mounting assembly be devised which provides for ease of card insertion while ensuring accurate alignment. An assembly to facilitate card mounting in this fashion should be modular in design and mass producible at low cost. Moreover, there should be a relatively high degree of compatability and interchangeability among the various assembly pieceparts.